FilterConfigDecoder.java

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/*
 * Gridarta MMORPG map editor for Crossfire, Daimonin and similar games.
 * Copyright (C) 2000-2015 The Gridarta Developers.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package net.sf.gridarta.model.filter;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public class FilterConfigDecoder {

    @NotNull
    private final StringBuilder sb = new StringBuilder();

    @NotNull
    private final FilterConfigVisitor visitor = new FilterConfigVisitor() {

        @Override
        public void visit(@NotNull final NamedFilterConfig filterConfig) {
            filterConfig.accept(resetToDefaultsVisitor);
            filterConfig.getFilter().resetConfig(filterConfig);

            final boolean enabled = removePrefix("enabled");
            filterConfig.setEnabled(enabled);
            boolean first = !enabled;

            final boolean inverted;
            if (first) {
                inverted = removePrefix("inverted");
            } else {
                inverted = removePrefix(",inverted");
            }
            if (inverted) {
                first = false;
            }
            filterConfig.setInverted(inverted);

            while (true) {
                if (sb.length() == 0 || sb.charAt(0) == ')') {
                    break;
                }
                if (first) {
                    first = false;
                } else {
                    if (!removePrefix(",")) {
                        break;
                    }
                }
                final String key = FilterCodecUtils.decodeString(sb);
                final FilterConfig<?, ?> subFilterConfig = filterConfig.getEntries().get(key);
                if (subFilterConfig == null) {
                    throw new NumberFormatException("filter has no key '" + key + "'");
                }
                if (!removePrefix("=")) {
                    throw new NumberFormatException("syntax error");
                }
                decodeInternal(subFilterConfig);
            }
        }

        @Override
        public void visit(@NotNull final NamedGameObjectMatcherFilterConfig filterConfig) {
            filterConfig.accept(resetToDefaultsVisitor);

            final boolean enabled = removePrefix("enabled");
            filterConfig.setEnabled(enabled);
            boolean first = !enabled;

            while (true) {
                if (sb.length() == 0 || sb.charAt(0) == ')') {
                    break;
                }
                if (first) {
                    first = false;
                } else {
                    if (!removePrefix(",")) {
                        throw new NumberFormatException("syntax error");
                    }
                }
                final String key = FilterCodecUtils.decodeString(sb);
                if (!removePrefix("=")) {
                    throw new NumberFormatException("syntax error");
                }
                filterConfig.setProperty(key, FilterCodecUtils.decodeString(sb));
            }
        }

    };

    @NotNull
    private final FilterConfigVisitor resetToDefaultsVisitor = new FilterConfigVisitor() {

        @Override
        public void visit(@NotNull final NamedFilterConfig filterConfig) {
            filterConfig.setEnabled(false);
            filterConfig.setInverted(false);
            filterConfig.getFilter().resetConfig(filterConfig);
            filterConfig.getEntries().values().forEach(entry -> entry.accept(resetToDefaultsVisitor));
        }

        @Override
        public void visit(@NotNull final NamedGameObjectMatcherFilterConfig filterConfig) {
            filterConfig.setEnabled(false);
            filterConfig.removeAllProperties();
        }

    };

    @Nullable
    private FilterConfig<?, ?> filterConfig;

    public boolean decode(@NotNull final String string, @NotNull final FilterConfig<?, ?> filterConfig) {
        sb.setLength(0);
        sb.append(string);
        try {
            decodeInternal(filterConfig);
        } catch (final IndexOutOfBoundsException | NumberFormatException ignored) {
            return false;
        }
        return sb.length() == 0;
    }

    private void decodeInternal(@NotNull final FilterConfig<?, ?> filterConfig) {
        final FilterConfig<?, ?> prevFilterConfig = this.filterConfig;
        try {
            if (!removePrefix("(")) {
                filterConfig.accept(resetToDefaultsVisitor);
                return;
            }
            this.filterConfig = filterConfig;
            filterConfig.accept(visitor);
            if (!removePrefix(")")) {
                throw new NumberFormatException("syntax error");
            }
        } finally {
            this.filterConfig = prevFilterConfig;
        }
    }

    private boolean removePrefix(@NotNull final String string) {
        final int length = string.length();
        if (length > sb.length() || !sb.substring(0, length).equals(string)) {
            return false;
        }

        sb.delete(0, length);
        return true;
    }

}